2001 $1 Centenary of the Australian Army 'S' Mintmark Coin. This commemorative coin marks the Centenary of the Australian Army and pays tribute to the many Australians, past and present, who have served their country. Since its formation in March 1901, the Army has fought in every major world conflict of the Twentieth Century, most recently becoming heavily involved in UN peacekeeping and peace making activities. Please contact Adelaide Exchange Jewellers to find out more on this item.